The picture on the May 2013 cover of TIME Magazine was less than flattering: a self-absorbed teenager poses for a selfie with her smartphone.

The text that accompanied it was even harsher: “Millennials are lazy, entitled narcissists who still live with their parents.”

Three years later, and the stereotype of millennials as work-shy, lackadaisical egoists lives on. But a new study suggests it might be time to rethink our attitudes towards the “me, me, me generation”. Millennials are, it turns out, the biggest workaholics out there.

A generation of work martyrs

More than 5,600 Americans were interviewed as part of the study, which looked at attitudes towards taking time off work. Those who, for various reasons – guilt, pride or fear of being replaced – did not use their vacation allowance were identified as “work martyrs”.

The results show that contrary to previous stereotypes, millennials are more likely than other generations to be hooked on work: “More than four in 10 (43%) of work martyrs are millennials, compared to just 29% of overall respondents.”

The study also found that 24% of millennials forfeited vacation last year – meaning they didn’t use holiday days they were entitled to – compared to 19% of generation X and 17% of baby boomers.

Not only are millennials so dedicated to their job (or scared of losing it) that they don’t take holidays – they’re guilt-tripping those who do.

“They are significantly more likely than older generations to say they shame their co-workers (42%, compared to 24%) for taking a vacation.”

A stressed, unhappy bunch of workers

If the “lazy millennial” stereotype is wrong, that’s good news, right? Unfortunately not.

Those people who like to consider themselves work martyrs are more likely than their colleagues to feel stressed and unhappy at work, the survey found.

Just over 40% of people who said their jobs caused them stress said they wanted to be seen as work martyrs, compared to 30% of unstressed employees. And almost half (47%) of those who are unhappy at work said they thought it was good to be a work martyr, compared to 38% of people who are happy in their jobs.

And it’s not just bad for the work martyrs themselves. As millennials move into the ranks of management, they’re starting to apply the same unrealistic pressures to those under them. Almost half (47%) of millennial managers said they sometimes refused time-off requests because of company pressure. Compare that to just 34% of generation X managers and 37% of boomers.

Victims of circumstance

So is this just more finger-pointing at millennials? While the report does call on work martyrs to “reconsider their approach” because it is “fundamentally flawed and poisonous to company cultures” it also recognizes that they are victims of circumstance.

“Coming of age during an economic downturn has consequences. When millennials landed jobs, they brought with them a strong desire to prove themselves, intensified by the often long and painful search that preceded their first day.”

But whatever the causes of this work-martyrdom, as the business leaders of tomorrow, millennials owe it to future generations to break this bad habit. “America’s vacation future hinges on its youngest professional generation.”